Ananova:

Britney Spears is making her pop comeback - by guesting on hubby Kevin Federline's debut album.

The 24-year-old popstar, who quit the music business after her 2004 Onyx Hotel Tour ended

to get married and start a family, sings back-up vocals on several tracks on Federline's upcoming album.

Federline, 27, told Ryan Seacrest's Los Angeles radio show on Thursday that Britney sings, but doesn't rap on his hip-hop album.

The as-yet-untitled album still has no official release date, but Federline says he hopes it will be out in the Spring.

The first official single, PopoZao, Brazilian slang for big-butt, is available for download on music.yahoo.com, MTV reported.

Federline also denied reports that Britney had kicked him out of their home and taken away his Ferrari calling the tabloids "just blah".